This invention relates to plastic film laminators of the type used for applying protective coverings to drivers licenses, identification cards, menus, photographs and other products formed of laminated plastic film. Such products typically comprise a paper card or the like placed between layers of plastic film such as polyethylene-coated Mylar. The plastic layers extend somewhat beyond the edges of the card. When the edges of the plastic layers are sealed by heating a protective pocket is formed around the card.
Generally, there are two main types of laminating machines. In smaller machines, heating of the plastic film to aid in lamination is accomplished by means of flat platens. An early example of a flat platen laminator is Elliott U.S. Pat. No. 2,927,620. A more recent example is Levitan U.S. Pat. No. 3,770,550. The other basic type of laminating machine uses heated rollers in the lamination process. These are usually larger machines. An example is Eisner U.S. Pat. No. 3,027,285.
In either a flat platen laminator or a heated roller laminator, probably the most expensive individual component is the heater. Conventionally, in a flat platen laminator, the heated platen is formed of metal with an electrically conductive heating element mounted on the side of the platen opposite that past which the plastic film moves. The surface of the platen may be treated or coated to reduce friction with respect to the plastic film that must pass over the platen. In some machines pressure is applied to the plastic as it traverses the platen. Perhaps more frequently, the pressure is effected with pressure rolls located immediately beyond the heating platen.
A similar situation applies with respect to heated roller laminators. Again, the heating element may be a conductive wire, in this instance wound around a shaft or other like support and covered over with an outer shell that constitutes the contact element with the plastic film. The outer shell on the heated laminator roll may be metal or it may be resin. Again, there may be a coating to minimize friction with the plastic film. The heated laminator roll may be a part of a pressure-applying mechanism or the pressure may be applied immediately after the plastic film traverses the heater roll.